/* $NetBSD: nlist_elf32.c,v 1.39 2016/02/26 17:12:53 christos Exp $ */

/*
 * Copyright (c) 1996 Christopher G. Demetriou
 * All rights reserved.
 * 
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *          This product includes software developed for the
 *          NetBSD Project.  See http://www.NetBSD.org/ for
 *          information about NetBSD.
 * 4. The name of the author may not be used to endorse or promote products
 *    derived from this software without specific prior written permission.
 * 
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 * 
 * <<Id: LICENSE,v 1.2 2000/06/14 15:57:33 cgd Exp>>
 */

#include <sys/cdefs.h>
#if defined(LIBC_SCCS) && !defined(lint)
__RCSID("$NetBSD: nlist_elf32.c,v 1.39 2016/02/26 17:12:53 christos Exp $");
#endif /* LIBC_SCCS and not lint */

/* If not included by nlist_elf64.c, ELFSIZE won't be defined. */
#ifndef ELFSIZE
#define ELFSIZE         32
#endif

#include "namespace.h"
#include <sys/param.h>
#include <sys/mman.h>
#include <sys/stat.h>
#include <sys/file.h>
#include <sys/ioctl.h>

#include <assert.h>
#include <errno.h>
#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include <nlist.h>

#include "nlist_private.h"
#if defined(NLIST_ELF32) || defined(NLIST_ELF64)
#include <sys/exec_elf.h>
#endif

#include <sys/ksyms.h>          /* after sys/exec_elf.h */

#if (defined(NLIST_ELF32) && (ELFSIZE == 32)) || \
    (defined(NLIST_ELF64) && (ELFSIZE == 64))

/* No need to check for off < 0 because it is unsigned */
#define check(off, size)        (off + size > mappedsize)
#define BAD                     goto out
#define BADUNMAP                goto unmap

int
ELFNAMEEND(__fdnlist)(int fd, struct nlist *list)
{
        struct stat st;
        Elf_Ehdr ehdr;
#if defined(_LP64) || ELFSIZE == 32 || defined(ELF64_MACHDEP_ID)
#if (ELFSIZE == 32)
        Elf32_Half nshdr;
#elif (ELFSIZE == 64)
        Elf64_Word nshdr;
#endif
        /* Only support 64+32 mode on LP64 and those that have defined */
        /* ELF64_MACHDEP_ID, otherwise no support for 64 mode on ILP32 */
        Elf_Ehdr *ehdrp;
        Elf_Shdr *shdrp, *symshdrp, *symstrshdrp;
        Elf_Sym *symp;
        Elf_Off shdr_off;
        Elf_Word shdr_size;
        struct nlist *p;
        char *mappedfile, *strtab;
        size_t mappedsize, nsyms;
        int nent;
#endif
        int rv;
        size_t i;

        _DIAGASSERT(fd != -1);
        _DIAGASSERT(list != NULL);

        rv = -1;

        /*
         * If we can't fstat() the file, something bad is going on.
         */
        if (fstat(fd, &st) < 0)
                BAD;

        /*
         * Map the file in its entirety.
         */
        if ((uintmax_t)st.st_size > (uintmax_t)SIZE_T_MAX) {
                errno = EFBIG;
                BAD;
        }

        /*
         * Read the elf header of the file.
         */
        if ((ssize_t)(i = pread(fd, &ehdr, sizeof(Elf_Ehdr), (off_t)0)) == -1)
                BAD;

        /*
         * Check that the elf header is correct.
         */
        if (i != sizeof(Elf_Ehdr))
                BAD;
        if (memcmp(ehdr.e_ident, ELFMAG, SELFMAG) != 0 ||
            ehdr.e_ident[EI_CLASS] != ELFCLASS)
                BAD;

        switch (ehdr.e_machine) {
        ELFDEFNNAME(MACHDEP_ID_CASES)

        default:
                BAD;
        }
#if defined(_LP64) || ELFSIZE == 32 || defined(ELF64_MACHDEP_ID)
        symshdrp = symstrshdrp = NULL;

        /* Only support 64+32 mode on LP64 and those that have defined */
        /* ELF64_MACHDEP_ID, otherwise no support for 64 mode on ILP32 */
        if (S_ISCHR(st.st_mode)) {
                const char *nlistname;
                Elf_Sym sym;

                /*
                 * Character device; assume /dev/ksyms.
                 */
                nent = 0;
                for (p = list; !ISLAST(p); ++p) {
                        struct ksyms_gsymbol kg;
                        int error;

                        p->n_other = 0;
                        p->n_desc = 0;
                        nlistname = N_NAME(p);
                        if (*nlistname == '_')
                                nlistname++;

                        memset(&kg, 0, sizeof(kg));
                        kg.kg_name = nlistname;
#ifdef OKIOCGSYMBOL
                        struct ksyms_ogsymbol okg;
                        error = ioctl(fd, KIOCGSYMBOL, &kg);
                        if (error == 0) {
                                sym = kg.kg_sym;
                        } else if (error && errno == ENOTTY) {
                                memset(&okg, 0, sizeof(okg));
                                okg.kg_name = nlistname;
                                okg.kg_sym = &sym;
                                error = ioctl(fd, OKIOCGSYMBOL, &okg);
                        }
#else
                        kg.kg_sym = &sym;
                        error = ioctl(fd, KIOCGSYMBOL, &kg);
#endif
                        if (error == 0
#if !defined(_LP64) && ELFSIZE == 64
#if __mips__
                            && (intptr_t)sym.st_value == (intmax_t)sym.st_value
#else
                            && (uintptr_t)sym.st_value == sym.st_value
#endif
#endif
                            && /*CONSTCOND*/1) {
                                p->n_value = (uintptr_t)sym.st_value;
                                switch (ELF_ST_TYPE(sym.st_info)) {
                                case STT_NOTYPE:
                                        p->n_type = N_UNDF;
                                        break;
                                case STT_COMMON:
                                case STT_OBJECT:
                                        p->n_type = N_DATA;
                                        break;
                                case STT_FUNC:
                                        p->n_type = N_TEXT;
                                        break;
                                case STT_FILE:
                                        p->n_type = N_FN;
                                        break;
                                default:
                                        p->n_type = 0;
                                        /* catch other enumerations for gcc */
                                        break;
                                }
                                if (ELF_ST_BIND(sym.st_info) != STB_LOCAL)
                                        p->n_type |= N_EXT;
                        } else {
                                nent++;
                                p->n_value = 0;
                                p->n_type = 0;
                        }
                }
                return nent;
        }

        mappedsize = (size_t)st.st_size;
        mappedfile = mmap(NULL, mappedsize, PROT_READ, MAP_PRIVATE|MAP_FILE,
            fd, (off_t)0);
        if (mappedfile == (char *)-1)
                BAD;

        /*
         * Make sure we can access the executable's header
         * directly, and make sure the recognize the executable
         * as an ELF binary.
         */
        if (check(0, sizeof *ehdrp))
                BADUNMAP;
        ehdrp = (Elf_Ehdr *)(void *)&mappedfile[0];

        /*
         * Find the symbol list and string table.
         */
        nshdr = ehdrp->e_shnum;
        shdr_off = ehdrp->e_shoff;
        shdr_size = ehdrp->e_shentsize * nshdr;

        if (check(shdr_off, shdr_size) ||
            (sizeof *shdrp != ehdrp->e_shentsize))
                BADUNMAP;
        shdrp = (void *)&mappedfile[(size_t)shdr_off];

        for (i = 0; i < nshdr; i++) {
                if (shdrp[i].sh_type == SHT_SYMTAB) {
                        symshdrp = &shdrp[i];
                        symstrshdrp = &shdrp[shdrp[i].sh_link];
                }
        }

        /* Make sure we're not stripped. */
        if (symshdrp == NULL || symshdrp->sh_offset == 0)
                BADUNMAP;

        /* Make sure the symbols and strings are safely mapped. */
        if (check(symshdrp->sh_offset, symshdrp->sh_size))
                BADUNMAP;
        if (check(symstrshdrp->sh_offset, symstrshdrp->sh_size))
                BADUNMAP;

        symp = (void *)&mappedfile[(size_t)symshdrp->sh_offset];
        nsyms = (size_t)(symshdrp->sh_size / sizeof(*symp));
        strtab = &mappedfile[(size_t)symstrshdrp->sh_offset];

        /*
         * Clean out any left-over information for all valid entries.
         * Type and value are defined to be 0 if not found; historical
         * versions cleared other and desc as well.
         *
         * XXX Clearing anything other than n_type and n_value violates
         * the semantics given in the man page.
         */
        nent = 0;
        for (p = list; !ISLAST(p); ++p) {
                p->n_type = 0;
                p->n_other = 0;
                p->n_desc = 0;
                p->n_value = 0;
                ++nent;
        }

        for (i = 0; i < nsyms; i++) {
                for (p = list; !ISLAST(p); ++p) {
                        const char *nlistname;
                        char *symtabname;

                        /* This may be incorrect */
                        nlistname = N_NAME(p);
                        if (*nlistname == '_')
                                nlistname++;

                        symtabname = &strtab[symp[i].st_name];

                        if (!strcmp(symtabname, nlistname)) {
                                /*
                                 * Translate (roughly) from ELF to nlist
                                 */
                                p->n_value = (uintptr_t)symp[i].st_value;
                                switch (ELF_ST_TYPE(symp[i].st_info)) {
                                case STT_NOTYPE:
                                        p->n_type = N_UNDF;
                                        break;
                                case STT_OBJECT:
                                case STT_COMMON:
                                        p->n_type = N_DATA;
                                        break;
                                case STT_FUNC:
                                        p->n_type = N_TEXT;
                                        break;
                                case STT_FILE:
                                        p->n_type = N_FN;
                                        break;
                                default:
                                        /* catch other enumerations for gcc */
                                        break;
                                }
                                if (ELF_ST_BIND(symp[i].st_info) != STB_LOCAL)
                                        p->n_type |= N_EXT;
                                p->n_desc = 0;                  /* XXX */
                                p->n_other = 0;                 /* XXX */

                                if (--nent <= 0)
                                        goto done;
                                break;  /* into next run of outer loop */
                        }
                }
        }

done:
        rv = nent;
unmap:
        munmap(mappedfile, mappedsize);
#endif /* _LP64 || ELFSIZE == 32 || ELF64_MACHDEP_ID */
out:
        return (rv);
}

#endif